Viking TDR-1 Time Delay Relay 8 Selectable Delays DPDT

Viking Electronics TDR-1 Time Delay Relay

Overview

The Viking Electronics TDR-1 is a compact time delay relay designed for door-release sequencing, interlock logic, and automated trigger applications in commercial access control and security installations. With eight selectable delay intervals spanning 1 to 30 seconds and a Double Pole, Double Throw (DPDT) output, the TDR-1 gives integrators precise control over timed switching events without requiring a programmable controller or custom wiring scheme. It accepts either a logic-level input (+5 VDC) or a dry contact closure, making it straightforward to drop into existing access control systems or intercom panels. The TDR-1 (often searched as TDR 1) ships with a 120V AC to 12V DC adapter, so you're powered up on the bench immediately.

Key Features

• Eight DIP-Selectable Delay Times (1–30 Seconds): Rather than a continuous pot that drifts over time, the TDR-1 uses DIP switch selection across eight preset intervals. That means the delay you set on the bench stays set in the field — no recalibration after thermal cycling or vibration.
• DPDT Relay Output — 1A @ 30VDC / 0.3A @ 110VDC / 0.5A @ 125VAC: The double-pole configuration lets you control two separate circuits simultaneously with one trigger event — useful when you need to release a door strike AND signal a status indicator at the same time. Verify your load: the 0.5A @ 125VAC ceiling means this is suited for low-current loads. Do not use directly on high-inrush motor loads.
• Dual Input Modes — Logic Level (+5VDC) or Contact Closure: Whether you're triggering from a microcontroller output, a relay output from an access panel, or a simple pushbutton, the TDR-1 accepts both without additional interface hardware. That flexibility keeps installation clean across mixed-signal environments.
• Included 120V AC to 12V DC Power Adapter: The adapter is in the box — you're not sourcing a wall-wart separately or hoping the panel has spare 12V capacity. For installations with limited auxiliary power headroom on the main panel, this matters.
• Compact Form Factor — 74mm x 53mm x 25mm (2.9" x 2.1" x 1.0"): At roughly the footprint of a deck of cards and just 25mm deep, the TDR-1 fits inside a standard single-gang back box or mounts in a small enclosure alongside other relay modules without consuming rack space.
• Operating Temperature 0°C to 32°C (32°F to 90°F): This is an indoor-rated device. The 32°C ceiling is a real constraint — unventilated equipment closets in warm climates can exceed that. Plan enclosure ventilation accordingly or route to a conditioned space.
• Operating Humidity 5% to 95% Non-Condensing: Wide humidity tolerance handles typical HVAC-controlled interior environments, but condensing conditions (think a basement door propping open in winter) are out of scope. Seal the enclosure if the installation is near a thermal boundary.

Integration & Compatibility

The TDR-1 integrates into any system that can provide a momentary contact closure or a +5VDC logic pulse as a trigger. Common deployment points in door control applications include: post-release delay on electromagnetic locks (hold the strike energized for a defined dwell period), sequenced relay chaining with Viking intercoms and Viking Electronics door entry products, and auxiliary output control on access panels that lack onboard delay logic. Because the DPDT output is electrically isolated from the input, it works safely as an interface between low-voltage logic and higher-voltage switched loads (within the relay's rated limits). Review the security relay and module category for companion devices if your application requires multiple delay stages or higher switching capacity.

Frequently Asked Questions

Q: What are the eight selectable delay times on the TDR-1?

A: The TDR-1 offers eight DIP-selectable delay intervals within the 1 to 30 second range. The exact preset values for each DIP position are defined in the Viking Electronics TDR-1 datasheet available from the manufacturer.

Q: Can the TDR-1 be used to delay an electromagnetic door lock release?

A: Yes. The DPDT relay output (rated 1A @ 30VDC or 0.5A @ 125VAC) is compatible with low-current electromagnetic lock and door strike loads. Confirm the lock's inrush and holding current fall within the relay's ratings before wiring.

Q: Does the TDR-1 require an external power supply?

A: No. A 120V AC to 12V DC power adapter is included with the TDR-1. You do not need to source a separate power supply for bench or field installation.

Q: What input signal does the TDR-1 accept to trigger the delay?

A: The TDR-1 accepts either a logic-level voltage (+5VDC) or a dry contact closure as the trigger input. This makes it compatible with both microcontroller outputs and standard relay/panel dry contacts without additional interface hardware.

Q: Is the TDR-1 suitable for outdoor installations?

A: No. The TDR-1 is rated for indoor use only, with an operating temperature range of 0°C to 32°C (32°F to 90°F) and no environmental ingress protection rating. It must be installed in a conditioned, enclosed indoor location.

Q: What is the physical size of the TDR-1?

A: The TDR-1 measures 74mm x 53mm x 25mm (2.9 inches x 2.1 inches x 1.0 inch) and weighs 0.86 lbs (0.4 kg). It fits comfortably inside a single-gang back box or small relay enclosure.

Jerry Tildsen

The TDR-1 is the kind of utility component that solves a very specific problem cleanly: you need a timed delay between a trigger event and a switched output, and you want to set it once with a DIP switch and forget it. The eight selectable intervals — all within the 1 to 30 second window — cover the vast majority of door-release dwell times and interlock sequencing requirements I encounter in commercial access control work, without any programming overhead.

Technical Highlights:

• DPDT Output at 1A/30VDC: Two independent switched circuits from one trigger event. This is the spec that makes the TDR-1 useful for simultaneous lock release plus status signaling — one relay pole releases the strike, the other toggles an indicator relay or a panel input, all from the same timed event.
• Dual Trigger Input (+5VDC logic or contact closure): No level-shifting hardware needed whether you're coming off a microcontroller GPIO, an access panel's AUX output, or a simple pushbutton. Both input types connect directly — that simplicity is the point.
• Compact 74mm x 53mm x 25mm Body: At 25mm deep, this fits in the same back box as the door hardware it's controlling. No separate enclosure required for typical installs, which keeps the wiring tidy and the wall cutout count down.

Deployment Considerations:

• The 120V AC adapter is included, but it occupies a standard outlet. In equipment closets where outlet count is already tight, factor that in during rough-in — or plan to use a power strip with surge protection.
• The 32°C upper temperature limit is the constraint most likely to bite you. Unventilated AV/security enclosures in commercial buildings regularly hit 35–40°C in summer. If your enclosure isn't actively ventilated, measure ambient temps before committing to this mounting location.

For Viking intercom and door entry panel installations where the panel lacks onboard adjustable delay logic, the TDR-1 is a clean, purpose-built solution — particularly in multi-tenant residential or small commercial lobby deployments where a 3–10 second door dwell is all that's needed to keep the install simple and code-compliant.